The present invention relates generally to medical apparatus; more particularly, to foot-operated controls for surgical apparatus. Numerous type of apparatus include as part of the apparatus, a connected, hand-held medical implement or tool. Operation of the tool requires control of various operating parameters or functions.
An example of such medical apparatus, is a phacoemulsifier apparatus which is especially constructed for surgically removing the natural, crystalline lenses from cataract eyes in preparation for the insertion of an artificial intraocular lens. Phacoemulsifier apparatus typically comprise a cabinet, which contains a power supply, vacuum pump, electronic, and associated hardware, and a connected multi-function, hand-held surgical implement having a slender hollow needle-like tube which is inserted into a patients eye in order to perform the phacoemulsion operation.
Functions of the phacoemulsifier hand-held surgical implement include irrigating the eye (with a saline solution), ultrasonically emulsifying (disintegrating) the eye lens, aspirating (by vacuum) the emulsified lens, cauterizing broken blood vessels, and vitretomy (removing vitreous humor from the eye). It can be appreciated that a surgeon using the hand-held implement to perform such functions requires the ability to control these functions, as well as the ability to selectively shift or switch between at least some of the functions (for example, irrigation and irrigation pulse aspiration) as the need arises during phacoemulsion surgery.
It should be appreciated that complete controlling and/or shifting of functions of a phacoemulsification handpiece from a remote, cabinet-mounted controls is generally unsatisfactory. Normally, a surgeon using the handpiece is too involved in the medical procedure to be able to operate remotely located, cabinet-mounted controls. On the other hand, having an attendant operate the cabinet-mounted controls is even less practical except, perhaps, for simple medical procedures and apparatus.
Such problems associated with adjusting cabinet-mounted controls while operating an associated hand-held medical implement may be overcome, in some simple cases, by mounting controls directly on the hand-held implement. This may, for example, be satisfactory when the only control required is to turn a function performed by the hand-held implement on and off and/or to vary an operational speed of a function performed by the implement. Then, included on the implement of a ON/OFF microswitch perhaps with the additional inclusion of speed control, may be feasible for some medical apparatus. However, phacoemulsification procedures performed by a skilled surgeon requires extremely precise control and, therefore, attempting to control a function with the same hand that is simultaneously manipulating the hand-held implement to perform a delicate operation is generally not preferred.
As an alternative (or a supplement) to cabinet-mounted and/or hand-held implement-mounted controls foot controls are frequently provided for medical (and other) apparatus, thereby freeing an operator""s hands so that he or she can concentrate on manipulating hand-held implement. Some such foot pedal controls, for example, have heretofore used one or more electrical switches mounted along the path of pedal movement so as to enable one or more operational functions to be respectively turned on and off by the operator depressing and releasing the foot pedal. In addition or alternatively, electric potentiometers have heretofore been connected to the pedal to enable the varying of an operational function by analog means according to the angle through which the pedal is displaced by the operator.
Mechanical detents are also known to have been used for providing increased resistance to angular pedal movement at preestablshed detent points, thereby providing a sensory warning to the operator that slightly further pedal depressing will cause a given event to occur. For example, such detents may be used to alert the operator to the turning off of one operational function and the turning on of another function by a control switch or switches mounted in the path of pivotal pedal movement.
This warning, or indication, is important in phacoemulsification surgery where various sequences of operations are required, such as, for example:
i) irrigation of the eye with a saline solution;
ii) a combination of simultaneous irrigation and aspiration of the irrigating fluid; and
iii) a combination of fluid irrigation and phacoemulsification power on the patient.
The footpedal may be used to control a function by a range of deflection or depression and to switch between functions by further depression. It is, of course, important that the operating surgeon be made aware of the switch, or transistor points.
Heretofore, the most commonly used tactile footpedal feedback is a clutch device controlled by a steppermotor. The motor exercises a torque when the footpedal is entering a specified a zone, or degree of depression. Thus, the surgeon will feel additional resistance at this point. Unfortunately, when the surgeon encounters additional torque at the transition zone, the physician will naturally exercise more torque which may cause premature entry into another function, or zone of operation.
An alternative method to provide feedback is through the use of a solenoid which is installed under the pedal. When the pedal is depressed at a transition point, the solenoid is powered to tap the footpedal. This has the advantage of providing no additional resistance to the pedal depression. However, this feedback system has a number of disadvantages. Namely, the vibration typically is noisy due to metal-to-metal contact which is unfavorable in a quiet operating room environment. Further, exercising the solenoid requires additional electrical power which may not be suitable for an intelligent footpedal with firmware incorporated. For example, see U.S. Pat. No. 4,983,901. Footpedals must be designed in accordance with safety regulation which requires them to sustain forces of 300 lbs/per square inch. This requirement requires a heavy mass which requires larger size solenoids and tremendous electrical power supply.
The present invention provides for improved sensory warning to a surgeon when utilizing a foot pedal requiring depression thereof to change operation or function at specific depressions, or transition points.
A surgical footpedal in accordance with the present invention generally includes a treadle size for receiving a user""s foot and adapted for enabling depression thereof in order to activate signals of control of associated surgical apparatus.
A vibrator is provided and disposed on the treadle for vibrating the treadle at selected treadle depression in order to provide sensory warning to the user that further treadle depression will cause a given event or occur.
A bracket attaches the vibrator to the treadle and causes resonant vibration of the treadle and the vibrator. This resonant operation is important in that it enables a very small vibrator, preferably an electric motor having a rotatable shaft and an eccentric weight attached to the shaft, to be utilized.
Preferably, the vibrator is disposed on an underside of the treadle and a bracket attaching the vibrator to the treadle underside, has an hourglass shape. That is, bracket is formed from elongate strip having a waist portion which is narrow than end portions of the strip.
The vibrator is attached to the bracket at the waist portion and the bracket is attached to the treadle proximate the end portions of the strip. In causing resonant vibration of the pedal and vibrator, the bracket thus functions as a vibrational, or mechanical or amplifier. This is important in view of the fact that the footpedal may have a weight exceeding 1.02 kilograms while the vibrator may weigh less than 6.5 grams. Thus, the weight of the treadle is at least about 31 times the total weight of the vibrator and the bracket.
The footpedal is adapted for depression through the use of a hinge for pivotally attaching the treadle to a base. The vibrator is disposed in a spaced apart relationship with the hinge and may be surrounded by a wall projecting from the treadle underside. A removable cover is provided for enclosing a wall, vibrator and the bracket in order to prevent environmental exposure. Preferably the treadle is angulated and the vibrator is disposed at an intersection of the angulated portions.